Inside a single-celled organism called a warnowiid is a sophisticated structure that looks just like an eye—an ocelloid. Ocelloids look so eye-like that, when they were first discovered in the warnowiid family of plankton, some thought they were eyes of jellyfish the plankton had eaten! Scientists led by University of British Columbia's Brian Leander have found out what ocelloids are really made of. They believe their discoveries shed light on warnowiid evolution and the evolution of eyes.
Complexity in Miniature
The ocelloid is "an amazingly complex structure for a single-celled organism to have evolved," says lead author Greg Gavelis. "It contains a collection of sub-cellular organelles that look very much like the lens, cornea, iris and retina of multicellular eyes found in humans and other larger animals." No comparable assemblage resembling a camera eye has ever been found inside any other unicellular organism. While many have eyespots — dots of photoreceptor pigment that capture light and enable a cell to orient itself in response to the light's direction and intensity — the ocelloid is unique.